<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>邮件测试</title>
</head>
<body>
    <div>
        <h2>这是一封测试模板的邮件</h2>
        <span>我是：${username}</span>
    </div>

</body>
</html>